diff --git a/internal/lsp/cache/check.go b/internal/lsp/cache/check.go
index ef547bf0cbf..8bd21b8d5ae 100644
--- a/internal/lsp/cache/check.go
+++ b/internal/lsp/cache/check.go
@@ -136,7 +136,11 @@ func (s *snapshot) buildKey(ctx context.Context, id packageID, mode source.Parse
 	// Begin computing the key by getting the depKeys for all dependencies.
 	var depKeys [][]byte
 	for _, depID := range depList {
-		depHandle, err := s.packageHandle(ctx, depID, source.ParseExported)
+		mode := source.ParseExported
+		if s.workspacePackages[depID] {
+			mode = source.ParseFull
+		}
+		depHandle, err := s.packageHandle(ctx, depID, mode)
 		if err != nil {
 			log.Error(ctx, "no dep handle", err, telemetry.Package.Of(depID))
 
diff --git a/internal/lsp/testdata/implementation/implementation.go b/internal/lsp/testdata/implementation/implementation.go
index 2b1070123a1..b4a98cc4929 100644
--- a/internal/lsp/testdata/implementation/implementation.go
+++ b/internal/lsp/testdata/implementation/implementation.go
@@ -1,6 +1,6 @@
 package implementation
 
-import "implementation/other"
+import "golang.org/x/tools/internal/lsp/implementation/other"
 
 type ImpP struct{} //@ImpP
 
@@ -25,5 +25,9 @@ type Foo struct {
 }
 
 type U interface {
-	U() //@mark(IntU, "U"),implementations("U", ImpU),
+	U() //TODO: fix flaky @implementations("U", ImpU)
 }
+
+type cryer int
+
+func (cryer) Cry(other.CryType) {} //@mark(CryImpl, "Cry")
diff --git a/internal/lsp/testdata/implementation/other/other.go b/internal/lsp/testdata/implementation/other/other.go
index e8410aff873..6fe16d4931a 100644
--- a/internal/lsp/testdata/implementation/other/other.go
+++ b/internal/lsp/testdata/implementation/other/other.go
@@ -19,3 +19,11 @@ type Foo struct {
 
 func (Foo) U() { //@mark(ImpU, "U")
 }
+
+type CryType int
+
+const Sob CryType = 1
+
+type Cryer interface {
+	Cry(CryType) //@implementations("Cry", CryImpl)
+}